POWER%20ELECTRONICS%20ECE%20105%20Industrial%20Electronics - PowerPoint PPT Presentation

View by Category
About This Presentation
Title:

POWER%20ELECTRONICS%20ECE%20105%20Industrial%20Electronics

Description:

POWER ELECTRONICS ECE 105 Industrial Electronics Engr. Jeffrey T. Dellosa College of Engineering and Information Technology Caraga State University – PowerPoint PPT presentation

Number of Views:147
Avg rating:3.0/5.0
Slides: 47
Provided by: NYP1
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: POWER%20ELECTRONICS%20ECE%20105%20Industrial%20Electronics


1
POWER ELECTRONICS ECE 105 Industrial Electronics
  • Engr. Jeffrey T. Dellosa
  • College of Engineering and Information Technology
  • Caraga State University
  • Ampayon, Butuan City

2
Power Electronics
  • Introduction
  • Power electronics is the technology of
    converting electric power from one form to
    another using power semiconductor devices based
    circuitry.
  • It incorporates concepts from analog circuits,
    electronic devices, control systems, power
    systems, magnetics, and electric machines.

3
Power Electronics
  • The converter enables either the following
  • DC-DC conversion
  • AC-DC rectification
  • DC-AC inversion
  • AC-AC cycloconversion

4
Power Electronics
  • In the power converter, the power semiconductor
    devices function as switches, which operate
    statically, that is, without moving contacts.
  • The time durations, as well as the turn ON and
    turn OFF operations of these switches are
    controlled in such a way that an electrical power
    source at the input terminals of the converter
    appears in a different form at its output
    terminals.

5
Power Electronics
  • Here power converter high conversion efficiency
    ? is essential!
  • High efficiency leads to low power loss within
    converter. Efficiency is a good measure of
    converter performance.
  • Hence, a goal of current converter technology is
    to construct converters of small size and weight,
    which process substantial power at high
    efficiency.

6
Power Electronics
  • Components used in power electronics circuitry
    are

7
Power Electronics
  • Rapid development of power semiconductor devices
    led to significant improvement in,
  • Speed
  • Power capability
  • Efficiency
  • Hence increase the range of applications
  • DC Servo control
  • AC motor control
  • Sophisticated power supplies (switching-mode,
    uninterruptible)
  • High power DC transmission

8
Power Electronics
  • Often power loss in power semiconductor device
    (when viewed as an ideal switch) is based on the
    following
  • Thus an ideal power semiconductor device is
    characterized by
  • zero resistance during ON-state, infinite
    resistance during OFF-state, zero transient time
    from ON to OFF and vice-versa.
  • Practical power semiconductor device has limited
    voltage and current handling capability, an
    ON-resistance greater than zero and finite
    switching times.

9
Power Electronics
  • Power Electronics Devices
  • Power Bipolar Transistors (BJTs)
  • Power Metal Oxide Semiconductor Field Effect
    Transistors (MOSFETs)
  • Insulated Gate Bipolar Transistors (IGBTs)
  • Thyristors
  • Gate Turn-Off Thyristors (GTOs)
  • Power Diodes

10
Power Electronics
11
Power Electronics
12
Power Electronics
  • Alternatively power semiconductor devices can be
    classified into 3 groups according to their
    degree of controllability.
  • Power Diodes - ON and OFF states controlled
    by the power cct.
  • Thyristors - Latched ON by a control signal but
    must be turned OFF by the power cct.
  • Controllable Switches - Turned ON and OFF by
    control signals.
  • The controllable switches include
  • i) BJTs
  • ii) MOSFETs
  • iii) Gate Turn-OFF Thyristors (GTOs)
  • iv) Insulated Gate Bipolar Transistors (IGBTs)

13
Power Electronics
  • Power Diodes

The circuit symbol for the diode and its steady
state v-i characteristics are as shown.
14
Power Electronics
  • Power Diodes

15
Power Electronics
  • Thyristors

The circuit symbol for the thyristor and its
steady state v-i characteristics are as shown.
16
Power Electronics
  • Thyristors

In its OFF state, the thyristor can block a
forward polarity voltage and not conduct, as is
shown by the off-state portion of the i-v
characteristic.
The thyristor can be triggered into the ON state
by applying a pulse of positive gate current for
a short duration provided that the device is in
its forward-blocking state. The resulting i-v
relationship is shown by the ON state portion of
the characteristics shown. The forward voltage
drop in the ON state is only a few volts
(typically 1-3V depending on the device blocking
voltage rating).
17
Power Electronics
  • Power BJTs

The circuit symbol for the BJTs and its steady
state v-i characteristics are as shown.
18
Power Electronics
  • Power BJTs

As shown in the i-v characteristics, a
sufficiently large base current results in the
device being fully ON. This requires that the
control circuit to provide a base current that is
sufficiently large so that
where hFE is the dc current gain of the device
BJTs are current-controlled devices, and base
current must be supplied continuously to keep
them in the ON state The dc current gain hFE is
usually only 5-10 in high-power transistors.
BJTs are available in voltage ratings up to
1400V and current ratings of a few hundred
amperes.
19
Power Electronics
  • Power BJTs
  • BJT has been replaced by MOSFET in low-voltage
    (lt500V) applications
  • BJT is being replaced by IGBT in applications at
    voltages above 500V

20
Power Electronics
  • Power MOSFETs

The circuit symbol for the MOSFETs and its steady
state v-i characteristics are as shown.
21
Power Electronics
  • Power MOSFETs
  • Power MOSFET is a voltage controlled device.
  • MOSFET requires the continuous application of a
    gate-source voltage of appropriate magnitude in
    order to be in the ON state.
  • The switching times are very short, being in the
    range of a few tens of nanoseconds to a few
    hundred nanoseconds depending on the device type.

22
Power Electronics
  • Power MOSFETs

23
Power Electronics
  • IGBTs

The circuit symbol for the IGBTs and its steady
state v-i characteristics are as shown.
24
Power Electronics
  • IGBTs
  • The IGBT has some of the advantages of the
    MOSFET, the BJT combined.
  • Similar to the MOSFET, the IGBT has a high
    impedance Gate, which requires only a small
    amount of energy to switch the device.
  • Like the BJT, the IGBT has a small ON-state
    voltage even in devices with large blocking
    voltage ratings (for example, VON is 2-3V in a
    1000-V device)..

25
Power Electronics
  • IGBTs

26
Power Electronics
  • Several Applications of Power Electronics

A laptop computer power supply system .
27
Power Electronics
  • Several Applications of Power Electronics

An electric vehicle power and drive system.
28
Power Electronics
  • Transient Protection of Power Devices

Snubber circuit limits
,
as well as voltage and peak current in a
switching device to safe specified limits!

Switching devices
rating is significant during the switching device
(e.g. thyristor) turn-OFF process. Voltage can
increase very rapidly to high levels. If the rate
rise is excessive, it may cause damage to the
device.
29
Power Electronics
  • Transient Protection of Power Devices

30
Power Electronics
  • Transient Protection of Power Devices

31
Power Electronics
  • Transient Protection of Power Devices

32
Power Electronics
  • Transient Protection of Power Devices

33
Power Electronics
  • Transient Protection of Power Devices

34
Power Electronics
  • Transient Protection of Power Devices

35
Power Electronics
  • Power and Harmonics in Non-sinusoidal Systems

Non-sinusoidal waveforms are waveforms that are
not sine waves.
,
Non-sinusoidal waveforms can be described as
being made of harmonics (multiple sine waves of
different frequencies).

Thus for a waveform whose fundamental frequency
is ?, than second harmonic has a frequency 2? and
so on.
Waveforms occurring at frequencies of 2?, 4?, 6?,
are called even harmonics Those occurring at
frequencies of 3?, 5?, 7?, ... are called odd
harmonics.
36
Power Electronics
  • Power and Harmonics in Non-sinusoidal Systems

Thus for the circuit shown (a non-sinusoidal
system), expressing the circuits voltage and
current as Fourier series
,

37
Power Electronics
  • Power and Harmonics in Non-sinusoidal Systems

,

38
Power Electronics
  • Power and Harmonics in Non-sinusoidal Systems

Expression for average power becomes
,

So power is transmitted to the load only when the
Fourier series of v(t) and i(t) contain terms at
the same frequency. Eg. if the voltage current
both contain 3rd harmonic, then they lead to the
average power
39
Power Electronics
  • Power and Harmonics in Non-sinusoidal Systems

With the rms voltage defined as
,

Inserting Fourier series into the above, an
expression of rms voltage for non-sinusoidal
voltage waveform
Notice harmonics always increase rms value
increased in rms values ? increased losses!
40
Power Electronics
  • Power and Harmonics in Non-sinusoidal Systems

For efficient transmission of energy from a
source to a load, it is desired to maximize
average power, while minimizing rms current and
voltage (and hence minimizing losses). Power
factor is a figure of merit that measures how
efficiently energy is transmitted. It is defined
as
,

Notice harmonics always increase rms value
increased in rms values ? increased losses!
41
Power Electronics
  • Basic Magnetics

Inductance (measured in Henry) is an effect which
results from the magnetic field that forms around
a current carrying conductor. Inductance can be
increased by looping the conductor into a coil
which creates a larger magnetic field.
,
An inductor is usually constructed as a coil of
copper wire, wrapped around a core either of air
or of ferrous material. Core materials with a
higher permeability than air confine the magnetic
field closely to the inductor, thereby increasing
the inductance. Inductors come in many shapes.
Most are constructed as enamel coated wire
wrapped around a ferrite bobbin with wire exposed
on the outside, while some enclose the wire
completely in ferrite and are called "shielded".
Some inductors have an adjustable core, which
enables changing of the inductance. Small
inductors can be etched directly onto a printed
circuit board by laying out the trace in a spiral
pattern.

42
Power Electronics
  • Basic Magnetics

Current flowing through an inductor creates a
magnetic field which has an associated
electromotive force (emf). This inductors emf
opposes the change in applied voltage. The
resulting current in the inductor resists the
change but does rise!
,
  • An inductor resists changes in current.
  • An ideal inductor would offer no resistance to
    direct current however, all real-world inductors
    have non-zero electrical resistance.


In general, the relationship between v(t) across
an inductor with inductance L and i(t) passing
through it is described by the differential
equation
The inductor is used as the energy storage device
in power electronics circuitries.
43
Power Electronics
  • Basic Magnetics

Transformers -- widely used in low-power
electronic ccts for voltage step-up or step-down,
for isolating DC from two ccts while
maintaining ac continuity. -- consists of 2
windings linked by a mutual magnetic field. When
one winding, the primary has an ac voltage
applied to it, a varying flux is developed the
amplitude of the flux is dependent on the applied
voltage and number of turns in the winding.
Mutual flux linked to the secondary winding
induces a voltage whose amplitude depends on the
number of turns in the secondary winding.
44
Power Electronics
  • Basic Magnetics

Mutual magnetic flux coupling is accomplished
simply with an air core but considerably more
effective flux linkage is obtained with the use
of a core of iron or ferromagnetic material with
higher permeability than air.
The relationship between voltage, current,
impedance between the primary secondary
windings of the transformer may be calculated
using the following relationships.
45
Power Electronics
  • Basic Magnetics

The basic phase relationship between the signals
at the transformer input output ports may be
in-phase, or out-of-phase. Conventionally, the
ports that are in-phase 1, and 3, are marked by
dot notation as shown.
46
Power Electronics
  • Basic Magnetics

EXAMPLE
About PowerShow.com